下列条件下，两种气体分子数一定不相等的是 [ ]

A．相同质量、不同密度的N₂O和CO₂

B．相同体积、相同密度的CO和C₂H₄

C．相同温度、相同压强、相同体积的O₂和O₃

D．相同压强、相同体积、相同质量的NO₂和N₂O₄

John’s pale face suggested that he ______ill, and his parents suggested that he ______a medical examination.

A．be, should have

B．was, have

C．should be, had

D．was, has